Sound-record.



J. FLETCHER.

SOUND RECORD.

APPLICATION FILED JULY 3.1915.

1,269,696., Patnt'ed June 18, 1918.

20 INVENTOR WITNESSES UNITED STATES PATENT OFFICE;

JOHN FLETCHER, OF DOUGLASTON, NEW YORK, ASSIGNOR TO OPERAPHONE MANUFAC-TURING CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SOUND-RECORD.

Specification of Letters Patent.

Patented June 18, 1918.

Application filed July 3, 1915. Serial No. 37,946.

It is well known that the sound records,

or talking machine records, now in general use, are divided into twotypes or classes which are known respectively as the hill and dale orvertically undulatory type and the 'zig zag or laterally undulatorytype. Records of the hill and dale type are usually provided ineach'case with an undulatory spiral groove of uneven depth form-- inghill and dale undulations correspondingto sound waves, and-records ofthe zig zag type are usually, provided in each case with an undulatoryspiral groove. of substantially uniform depth forming zig zag or lateralundulations corresponding to sound waves.

In the usual process of producing commercial'records of either the hilland dale or the zig zag type, it is customary to first form a masterrecord by cutting in a record blank of wax or other comparatively soft'wax-like material a suitable spiral groove by means of a suitablecutting tool or stylus vibr'atedby and in accordance with sound waves. Amatrix or negative is then made from the master record by anelectrotyping process and the commercial records are then formed bysubjecting normally comparatively hard record material, renderedtemporarily plastic by heat, to the action of the matrix under greatpressure, and then cooling the record material while under pressure.

It has been suggested that in recording hill and dale undulations in arecord that the resistance to the action of the recording,

stylus varies with the depth of the groove being cut whereas inrecording zig zag undulations there is no variation in resistance due tovariation in depth of cut as the depth of cut is constant.

It has also been suggested that in reproducing sound from a hill anddale record the bottom wall of the record groove has to perform not onlythe function of supporting the weight of the sound box but also thefunction ofvibrating the stylus and diaphragm and consequently issubjected to greater wear and must be considerably broader than thebottom of a zig zag record which is smooth and even and has to performonly the'function' of supporting the sound box.

Moreover, it has been suggested that the use of a wide sound groove informing a record is considered to be objectionable in that it requiresthe removal or displacement of'a relatively large amount of materialfrom the wax master record, and consequently causes a considerableresistance to the normal action of the recording stylus during therecording process; and that it is also objectionable in that itdiminishes the" spiral grooves than are usually provided in records ofthe'zig zag type and in an obvious efiort to economize space as much aspossible the spiral grooves of such hill and dale records have been soformed that the successive convolutions of the groove overlap or meet insharp edges, as will appear hereinafter.

This invention provides a hill and dale record, having an extremelynarrow undulatory groove, which may be used successfully in cooperationwith an ordinary conically pointed steelneedle in reproducing sound, andwhich has been found to be extremely durable in use and to havepractically all of the advantages of a zig zag record, and also certainother advantages, as will appear hereinafter.

In the accompanying drawings, Figure 1 is a greatly enlarged fragmentarytop plan view of a disk sound record constructed in accordance with thisinvention; Fig. 2 a transverse section of the same on line 2-2 of Fig.1; Fig. 3 a longitudinal section of the same on line 3-3 of Fig. 1; Fig.& a fragmentary top plan View of an old form of hill and dale soundrecord, drawn to substantially the same scale as Fig. 1; Fig.

5 a transverse section on line 5 5 of Fig. 4; and Fig. 6 a longitudinalsection on line 66 of Fig. 4. Referring to the drawings, one embodimentof this invention comprises a commercial disk sound record 10 formed inany well known or suitable manner of any usual or suitable material butpreferably of a substantially homogeneous material or composition whichis plastic when heated and hard when cooled and which contains a smallamount of a finely pulverized mild abrasive such for instance as china.clay or barytes, or any other suitable material. In the face of the diskrecord is formed in any well known or suitable manner a spiral groove 11in the form of vertical or hill and dale undulations corresponding tosound waves. This sound groove may be of any suitable form anddimensions, but {preferably in cross section is approximately orsubstantially in the form of a portion of an elhpse or slightlyflattened semi-circle arranged with its longer or major diameterextending either in the plane of the face of the record or in adirection parallel thereto, depending upon the depth of the groove atthe particular oint where the cross section is taken. Ordinarily at itsdeepest points the groove 11 in cross section is approximately orsubstantially in the form of a semi-ellipse or slightly flattenedsemi-circle and is slightly more than twice as wide as it is deep, butit is to be understood that this ratio between the maximum width and themaximum depth of groove may be: either increased or I decreased as maybe found desirable, and in some cases it may be found desirable to have.the maximum depth of the groove as great or even greater than themaximum width of the groove. In any case, however, the maximum width ofthe groove is preferably slightly less than the pitch of the spiral orthe distance from the center of one convolution of the spiral to thecenter of a succeedingconvolution, thus leaving at all times a spiralwall 12 having a flat top or outer surface 13 of appreciable widthbetween successive convolutions.

In the embodiment of this invention shown in Figs. 1, 2 and 3, thespiral record groove has 184 turns or convolutions to the inch, or inother words, the pitch of the groove is 1/184: of an inch (approximately.00543 plus of an inch) and the record groove has a maximum width ofapproximately .005 of an inch, thus leaving a spiral wall having a flatsurface 13, having a minimum width of .00043 plus between consecutiveconvolutions of the groove 11.

The commercial record 10. constructed in accordance with this invrntionmay be formed in any suitable manner but preferably by first cutting orotherwise forming in a soft record blank a hill and dale groove of thesame form and dimensions as that just described by means of any suitabletool but preferably by means of such a cutting tool as is shown in Figs.2 and 3 and which consists of a jewel having a cylindrical portion 15the free end of which is cupped out or countersunk as at 16 to provide asharp circular cutting edge 17. In forming the hill and dale groove 11the tool 15 is arranged in an inclined position as shown and is vibratedvertically by and in accordance with sound waves in a well known mannerwhile the record blank is suitably rotated and. is moved laterally withrespect to the tool to cause the tool to cut a hill and dale spiralgroove in the record blank. Commercial records are then made from thesoft master record in any well known manner, as, for instance, byforming a suitable electrotype either directly or indirectly from themaster record, backing up the electrotype and then utilizing theelectrotype for pressing the commercial records.

In forming a master sound record it is customary to permit the tool tocut or form several smooth preliminary convolutions of the record groovebefore the tool is subjected to the action of sound waves, and thesepreliminary convolutions serve to receive the stylus 0r needle at apoint prior to or in advance of the initial notes or sounds recordedupon the record and when the records are made of material which isslightly abrasive .and steel needles are used, these preliminaryconvolutions wear the point of the needle slightly and shape it to thegroove.

It has ben found that commercial sound records constructed in accordancewith this invention of any suitable record material but preferably of amaterial which is slightly abrasive, are well adapted to be used incooperation with ordinary conically pointed needles such as aregenerally usedslides over the hill and dale sound undulations of thegroove Without any excessive wear either on the needle or on the record.

In Figs. 4c, 5 and 6 is shown very much en larged one of the old formsof hill and dale records in which the record 20 is provided with a hilland dale spiral groove 21 having 96 turns or convolutions to the inch ora pitch of 1/96 of an inch and in which the successive convolutionsoverlap and meet in sharp edges 22. In this old "form the maximum widthof the groove is considerably greater than the pitch of the groove andis considerably greater than twice the maximum depth of'the groove. Thegroove in this old form is originally formed ordinarily by a cylindricaltool 25 similar to the one hereinbefore described and having a. cuppedend 26 forming a shar circular edge 27, the diameter of which 13considerably greater than the pitch of the record groove 21.

It has been found-that, owing largely to the fact that .in making themaster record in accordance with this invention .a comparatively smallamount of resistance isencountered by the recording stylus or tool,commercial records constructed in accordance with this invention givevery superiorphonetic results, such for instance as improved detimtlonand brilliancy of tone, an

improved rendition of fine overtones and harmonics, a clear andcharacteristic reproduction of all of the various instruments and voicesin ensemble productions of grand operas, and other improved results.

It has also been found that by havinga flat wall of appreciable width orthickness between the successive convolutions of the record groove,these walls are not liable to become cracked or chipped either duringthe manufacture. of the records or during sub sequent use, whereas inthe old form of record shown in Figs. 4, 5 and 6 a large percentage ofthe records are spoiled during the process of manufacture by thecracking or chipping of the sharp edges 22between the record grooves 21while the records are being cooled suddenly while under compression,

anda further large percentage of these oldforms of records are spoiledwhile in use by the accidental chipping of these sharp edges 22.

Furthermore, in the new form of record shown in Figs. 1 to 3, the upperportions of the side walls of the record groove are either vertical orapproximately vertical at points where the groove has a maximum depth,and in any case have a steeper inclination than the side walls of thegroove 21 in the old form and consequently the walls of the groove inthe new form are of such a form as to serve as an effective guidingmeans for propelling the sound reproducing means across the record inreproducing sounds from the record, while in the old formths groove 21is so shallow in proportion to its width and is of such a shape that theWalls of the groove are not adapted to act efiectively to guide andpropel a sound reproducer, and require a mechanical feed for the soundreproducer to insure effective action.

Moreover, it is obvious that in the new form of record shown in Figs. 1,2 and 3. a

relatively large amount of sound measured in time may be recorded on arecord of given area, and there is therefore an appreciable economy ofmaterial which reduces the cost of the record both at the factory and intransportation and renders the record more convenient to handle and lessliable to be injured. It is also obvious that this improved record hasmany other advantages over the old form of hill and 'dale record shownin Figs. t to 6.

in a record of the zig zag type. For instance, in a zig zag recordhaving a record groove of 18% turns to the inch, the groove owing to itslaterally undulatory form could ordinarily have a widthof not more than2 or 3 thousandths of an inch and a depth of about the same amount andwould evidently provide a much smaller undulatory bearing surface thanis provided by the improved hill and dale record having a record grooveof 184 turns to the inch and a maximum width of about .005 as shown inFigs. 1 to 3, particularly as the bottom wall of a laterally undulatorygroove is smooth and of uniform depth and the vibration of the stylusand the feeding or propelling of the stylus across the record iseffected mainly if not entirely by the action of only one of the sidewalls of the groove.

While for the purposes of this invention it is preferred to form thisimproved record of material which is slightly abrasive, or whichcontains an abrasive, it is to be understood that it is not necessarythat an abrasive material be used as any other suitable material willgive satisfactory results.

Moreover, although this improved recordbeen shown and described in whichthis invention may be embodied, it is to be understood that theinvention is not limited in its application to any specific constructionbut might be embodied in various forms without departing from the spiritof the invention or the scope of the appended claims.

Claims.

Having thus fully described this invention, I claim and desire toprotect by Letters Patent of the United States:

1. A sound record having thereon a spiral groove comprising a pluralityof convolutions of uneven depth forming hill and dale undulationscorresponding to sound waves, and successive convolutions of said groovebeing separated at all points by a substantially fiat topped Wall, andsaid groove having a transverse sectional form which at a point ofmaximum width is substantially in the form of a slightly flattenedsemicircle.

2. A sound record having thereon a spiral groove comprising a pluralityof convolutions of uneven depth forming hill and dale undulationscorresponding to sound waves, and successive convolutions of said groovebeing separated at all points by a substantially fiat topped wall, saidgroove having a maximum width less than the pitch of said spiral butequal to a major portion of said pitch, and having a maximum depthordinarily approximating one-half of said of maximum width issubstantially in the form of a slightly flattened semicircle.

3. A sound record having thereon a spiral groove comprising a pluralityof convolutions of uneven depth forming hill and dale undulationscorresponding to sound waves, and successive convolutions of said groovebeing separated at all points by a substantially .flat topped wall, saidgroove 40 having a maximum Width less than the pitch of said spiral butequal to a major portion of said pitch, and having a maximum depthordinarily approximating one-half of said maximum width,and said spiralgroove having a pitch of'approximately one hundred eighty-four turns tothe inch and said groove having a transverse sectional form which at apoint of maximum width is substantially in the form of a slightlyflattened semicircle. Signed at New York, in the county of New York andState of New York this 29th day of June, A. D, 1915.

JOHN FLETCHER.

Witnesses:

A. I. GARDNER, K. Poms.

